2.0 SHEAR
2.2 Pryout Failure Mode
Calculations ψ cp , N
Calculations ACI 318-19 Chapter 17 Provision Comments for PROFIS Engineering
ψ cp , N
17.6.2.6.1 Modification factor for post-installed anchors designed for uncracked concrete in accordance with 17.6.2.5 without supplementary reinforcement to control splitting , ψ cp , N
, shall be determined by ( a ) or ( b ) using the critical distance cac as defined in 17.9.5 .
( a ) If c a , min ≥ c ac
, then ψ cp , N = 1.0 ( 17.6.2.6.1a )
( b ) If c a , min < c ac
, then ψ cp , N = c a , min
c ac
≥
1.5h ef ( 17 . 6 . 2 . 6 . 1b )
17.6.2.6.2 For all other cases , including cast-in anchors , ψ cp , N shall be taken as 1.0 . c ac
17.6 . 2 . 5.1 ……... For anchors located in a region of a concrete member where analysis indicates no cracking at service load levels ……………..
17.9.5 Critical edge distance cac shall be in accordance with Table 17.9.5 unless determined from tension tests in accordance with ACI 355.2 or ACI 355.4 .
Table 17.9.5 – Critical edge distance Post-installed anchor type Torque-controlled Displacement-controlled Screw Undercut
Critical edge distance c ac 4 h ef 4 h ef 4 h ef 2.5 h ef
The parameter ψ cp , N is only considered when designing post-installed anchors in uncracked concrete . ψ cp , N does not need to be calculated if the smallest fixed edge distance ( c a , min ) is greater than or equal to c ac
, or if cracked concrete conditions are assumed . Testing per the ICC-ES acceptance criteria AC193 and the ACI test standard ACI 355.2 is used to derive c ac values for mechanical anchors . Testing per the ICC-ES acceptance criteria AC308 and the ACI test standard ACI 355.4 is used to derive c ac values for adhesive anchor systems . c ac values derived from this testing are provided in an ICC-ES evaluation report ( ESR ). ACI 318-19 Table 17.9.5 provides c ac
-values for post-installed anchors ; however , these values are only intended to be used as “ guide values ” in the absence of c ac values derived from product-specific testing . PROFIS Engineering uses the c ac
-value that is given in the ICC-ES evaluation report for an anchor to calculate ψ cp , N
. The value for ψ cp , N that PROFIS Engineering calculates will be limited to
MAXIMUM { c a , min / c ac
: 1.5h ef
/ c ac }, where c a , min is the smallest fixed edge distance being modeled in the application and h ef is the effective embedment depth that has been selected for the anchor . “ ψ cp , N
” calculated for concrete breakout failure in tension is not necessarily the same as “ ψ cp , N
” calculated for concrete pryout failure in shear since the number of anchors in tension may not be the same as the number of anchors in shear . When calculating concrete breakout in tension , values for c ac should be checked against fixed edge distances relevant to anchors in tension . When calculating concrete pryout in shear , values for c ac should be checked against fixed edge distances relevant to anchors in shear . Consider : 4-anchors in tension and 6-anchors in shear .
Adhesive
2 h ef
Example of critical edge distance requirements given in a mechanical anchor approval .
ICC-ES ESR-1917 Table 3
DESIGN |
|
Nominal anchor diameter ( in .) |
|
INFORMATION Symbol Units
|
3 / 8 |
1 / 2 5 / 8 |
3 / 4 |
Effective min . embedment
Min . member thickness
Critical edge distance h ef in . 1-1 / 2 2 2-3 / 4 2 3-1 / 4 3-1 / 8 4 3-1 / 4 3-3 / 4 4-3 / 4 h min in . 3-1 / 4 4 5 5 4 6 6 8 5 6 8 5-1 / 2 6 8 8 c ac in . 6 4-3 / 8 4 4-1 / 8 5-1 / 2 4-1 / 2 7-1 / 2 6 6-1 / 2 8-3 / 4 6-3 / 4 12 10 8 9
232 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-19 Provisions